When President Donald Trump took office on January 20, the new administration's policy on North Korea was unclear.

Three months on, China's calling for calm amid warnings from Pyongyang's United Nations envoy of possible thermonuclear war, while the White House stresses that its long-held policy of "strategic patience" is over.

The day before Trump recited the oath of office on the Washington Mall, the North Korean leadership already had prepared its own unique welcome for the incoming President. On January 19, US intelligence satellites picked up signs of activity at North Korea's Chamjin missile factory southwest of Pyongyang, in an apparent readying of a test of two intercontinental ballistic missiles (ICBMs).

10 days later -- January 29 -- as Defense Secretary James Mattis prepared for his first visit to Asia, it was reported that the country was preparing to restart a plutonium reactor at the Yongbyon nuclear facility, according to analysis of new satellite imagery from 38 North, a North Korea tracking project.

February

The Trump administration kicked off the month with Mattis' East Asian jaunt, landing February 2 at the Osan Air Base outside Seoul. Top of the agenda was a key component of South Korea's defenses against its northern neighbors' aggression -- the THAAD missile interception system.

Three days later, February 5, the US and its East Asian ally Japan successfully downed a test medium-range ballistic missile with a new interceptor launched from a guided-missile destroyer.

North Korea didn't take long to respond. On February 11, it reported it had successfully completed the launch of a new ballistic missile, the previously unknown Pukguksong-2, according to state media. It was the North's first missile test of the Trump era.

Things took a twist worthy of a movie plot later that month. On February 14, alleged North Korean agents reportedly murdered Kim Jong Un's half brother, Kim Jong Nam, at Kuala Lumpur International Airport (KLIA) with VX nerve agent.

Shortly after, in the wake of the DPRK's missile test and the resultant growing tensions on the Korean Peninsula, China banned imports of Chinese coal for the remainder of the year. China's Ministry of Commerce said the decision was made to comply with a UN Security Council resolution that China helped draft and pass last November.

March

March was an even busier month for the Korean Peninsula. It kicked off, on March 6, with North Korea's firing of four ballistic missiles into the Sea of Japan (also known as the East Sea) in what Japanese Prime Minister Shinzo Abe described as "an extremely dangerous action."

The missiles, three of which landed within 200 miles of Japan's coastline in its exclusive economic zone, were fired as part of a drill targeting American military assets in Japan by North Korea's Hwasong artillery units, North Korean state media KCNA said.

On the heels of the multiple launch, South Korea's US-built THAAD missile defense system -- which China vigorously opposes -- arrives on the peninsula. As it was delivered, China's top diplomat, Foreign Minister Wang Yi, warns that the US and North Korea are set for a "head-on collision" with neither side willing to give way.

On March 14, the US, along with allies South Korea and Japan, responded to the North's earlier missile tests, dispatching high-tech missile defense ships to the same area where Pyongyang had previously fired the four missiles. The Aegis warships began exercises to improve their capability to shoot down enemy ballistic missiles, the US Navy said in a statement.

The maneuvers came as Secretary of State Rex Tillerson embarked upon his first Asian trip, landing in Japan on March 15.

Five days later, Pyongyang again ratcheted tensions by testing a rocket engine, one which showed "meaningful" signs of progress, according to South Korean officials.

Meanwhile, in the face of the looming threat from North Korea, Japan begins to hold evacuation drills to prepare for any potential North Korean missile launched aimed at the country.

The North Koreans launched another missile just days after the engine test, but it exploded "within seconds of launch," according to US Pacific Command. As March wound down, Pyongyang once again went back to its engine tests -- technology could possibly be used in an eventual ICBM.

In a separate move, the US announced that the US Marines deployed F-35B aircraft to South Korea for the first time as part of an exercise.

April

Trump began the month by declaring, on April 2, that the US would be willing to go it alone to restrain North Korea's nuclear weapons program should China fail to change the situation.

Two days later, as Trump prepared to meet his Chinese counterpart, President Xi Jinping, North Korea fired another ballistic missile off the coast of the Korean Peninsula, US and South Korean officials said. As the two leaders sat down to steak and pan-seared sole at Trump's Mar-a-Lago resort in Florida, Trump made the decision to pull the trigger on a missile strike in Syria -- the biggest military action of his presidency and a declaration of intent for Pyongyang.

Shortly after, North Korea issued a forceful response to the deployment of a US naval strike group, including the 97,000-ton carrier, the USS Carl Vinson, to the region April 10, saying it would counter "reckless acts of aggression" with "whatever methods the US wants to take."

Days later, monitoring group 38 North said its analysis had concluded that North Korea's Punggye-ri nuclear site is "primed and ready" for a sixth nuclear test. Also on April 13, Japanese Prime Minister Shinzo Abe said that the country may already have the capability to deliver missiles equipped with sarin nerve agent.

Meanwhile, the US waded again into military action, dropping a GBU-43/B Massive Ordnance Air Blast Bomb (MOAB), the US military's largest non-nuclear weapon, on an ISIS hideout in Afghanistan, the first time this type of weapon has been used in battle, according to US officials.

Two days later, at an annual military parade in Pyongyang, the North Korean regime showed off a bevy of new missiles and launchers at its annual military parade.

Part of the display were two new ICBM-sized canisters as well as North Korea's submarine-launched ballistic missile, and a land-based version of the same for the first time, according to analysts.

The following day, April 16, another attempted missile launch by the Kim regime failed, US and South Korean defense officials told CNN.

After the attempted test, US Vice President Mike Pence, visiting the South Korean side of the demilitarized zone (DMZ) on April 17, warned North Korea not to test the resolve of the US "or the strength of our military forces."

North Korea's UN deputy representative, Kim In Ryong, responded, warning that the US actions and rhetoric have "created a dangerous situation in which thermonuclear war may break out at any moment on the peninsula and poses a serious threat to world peace and security."

After boasting that the USS Carl Vinson strike group was being dispatched to the Korean Peninsula in a "show of force," the US was forced to walk back the claims after it emerged that the ships in question were actually on their way to participate in military exercises in the Indian Ocean, some 3,500 miles in the opposite direction.

Instead, the strike group will arrive off the Korean Peninsula by the end of April, multiple US defense officials told CNN.

The Pentagon announced on April 18 that it will conduct two major tests of its ability to shoot down missiles launched out of North Korea in May.

On April 19, the UN Security Council tried to address North Korea's latest missile launch with a proposed statement that would have condemned the test, but Russia used its veto to torpedo the motion.

The same day, Chinese Foreign Ministry spokesman Lu Kang said Beijing was "gravely concerned" about North Korea's recent nuclear and missile activities. Lu also praised recent US statements on the North Korean issue.

On April 20, the UN Security Council formally condemned North Korea's latest missile launch, demanding that it "immediately" cease further actions that violate resolutions. Russia denied it had previously blocked the action, saying that it wanted to add language to the document.

North Korea launched a missile April 29 that blew up over land, a US official said. The missile failed to reach the Sea of Japan, also known as the East Sea.

It was later confirmed the USS Carl Vinson aircraft carrier finally arrived in Korean waters, ready to begin drills with their South Korean counterparts.

To wrap up a tense month on the Korean Peninsula, Trump praised the North Korean leader, saying he had come to power at a young age and was a "smart cookie."

May

Trump began a new month of relations with North Korea on a more positive note, saying on May 1 he would be "honored" to meet with Kim Jong Un "under the right circumstances."

On the same day, US officials confirmed the controversial THAAD system was finally deployed and operational in South Korea.

The North Koreans fired a ballistic missile May 14 that landed in water 60 miles south of Russia's Vladivostok region, a US official told CNN.

It was the first provocative move from North Korea since South Korean President Moon Jae-in took office on May 10. Moon has advocated for engagement with North Korea to denuclearize the Korean Peninsula.

The launch came as Chinese leader Xi Jinping and multiple world leaders, including Russian President Vladimir Putin, attended a major trade and infrastructure summit in Beijing.